/************************************************************************
                                                                     
   Xceed Ultimate ListBox for Silverlight                                                                                                                                            
   Copyright (C) 2010 Xceed Software Inc.    
                                                                     
   This program is provided to you under the terms of the GNU General Public  
   License version 2 as published by the Free Software Foundation. 
        
   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY, without even the implied warranty of 
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License along 
   with this program, if not, write to the Free Software Foundation, Inc., 
   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

   This program can be provided to you by Xceed Software Inc. under a
   proprietary commercial license agreement for use in non-Open Source
   projects. Visit Xceed.com to find the commercial edition of 
   Xceed Ultimate ListBox for Silverlight.                                    
                                                                      
 **********************************************************************/

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Windows;
using System.Windows.Media;
using System.Diagnostics;

namespace Xceed.Silverlight.ListBox.PositioningFunction
{
  internal class PathPositioning : PositioningFunctionBase
  {
    #region Contructor
    internal PathPositioning( List<Point> pointsOnFlattenedPath,
      Rect pathBounds,
      Thickness padding,
      Stretch stretch,
      ContainerOrientation containerOrientation,
      double containerPadding,
      double startOffset )
    {
      this.Stretch = stretch;
      this.ContainerOrientation = containerOrientation;
      this.ContainerPadding = containerPadding;
      this.StartOffset = startOffset;
      this.PropertyChanged += new PropertyChangedEventHandler( OnPropertyChanged );

      m_padding = padding;

      // We mut keep the path's bound to be able to fit all the containers into the viewport 
      m_pointsOnFlattenedPath = pointsOnFlattenedPath;
      m_pathBound = pathBounds;

    }
    #endregion

    #region DisplayName Property

    internal override string DisplayName
    {
      get
      {
        return "Path Positioning function";
      }
    }

    #endregion

    #region Padding Property

    internal Thickness Padding
    {
      get
      {
        return m_padding;
      }
      set
      {
        if( m_padding != value )
        {
          m_padding = value;
          this.NotifyPropertyChanged( "Padding" );
        }
      }
    }

    private Thickness m_padding;

    #endregion

    #region ContainerPadding

    internal double ContainerPadding
    {
      get;
      private set;
    }

    #endregion

    #region Stretch Property

    internal Stretch Stretch
    {
      get;
      set;
    }

    #endregion

    #region ContainerOrientation Property

    internal ContainerOrientation ContainerOrientation
    {
      get;
      private set;
    }

    #endregion

    #region StartOffset Property

    public double StartOffset
    {
      get;
      private set;
    }

    #endregion

    #region ViewportCachedSize Property

    private Size ViewportCahcedSize
    {
      get
      {
        return m_viewportCachedSize;
      }

      set
      {
        if( m_viewportCachedSize != value )
        {
          m_viewportCachedSize = value;
          this.NotifyPropertyChanged( "ViewportCachedSize" );
        }
      }
    }

    #endregion

    #region Internal Methods
    internal override void PrepareLayoutPass( double partialOffset, Size itemContainerSize, Size groupContainerSize )
    {
      m_firstContainerLayouted = false;
      m_cachedPartialOffset = partialOffset;
      m_cachedItemContainerSize = itemContainerSize;
    }

    internal override void PlaceContainerForward( Size container,
      bool isGroupContainer,
      out Point containerPosition, 
      out double containerProportionInViewport,
      out int layoutProgressionPercentage,
      out double rotateAngle )
    {
      containerProportionInViewport = 1.0d;
      containerPosition = new Point();
      rotateAngle = 0.0d;

      double containerSpace = container.Width + this.ContainerPadding;

      if( !m_firstContainerLayouted )
      {
        double pixelsPartialOffset = 0.0;
        if( !isGroupContainer )
        {
          pixelsPartialOffset = m_cachedPartialOffset * containerSpace;
        }
        else
        {
          pixelsPartialOffset = m_cachedPartialOffset * ( containerSpace + m_cachedItemContainerSize.Width + this.ContainerPadding);
        }
        double startOffsetAbs = this.StartOffset * (this.EffectiveViewportEnd - this.EffectiveViewportStart);
        this.IndexPositionTopBottom = startOffsetAbs + this.StartOffsetIndex - pixelsPartialOffset;
        this.IndexPositionBottomUp = startOffsetAbs + this.StartOffsetIndex - pixelsPartialOffset;
        m_firstContainerLayouted = true;
      }

      double distanceFromPathBeginning = this.IndexPositionTopBottom - this.ExtendedViewportStart;

      this.GetPositionForDistance( distanceFromPathBeginning, m_fittingMatrix, out containerPosition, out rotateAngle );

      layoutProgressionPercentage = ( int )( ( distanceFromPathBeginning / m_pathTotalLength ) * 100.0d );

      containerProportionInViewport = this.GetContainerProportionInEffectiveViewport( container, new Point( this.IndexPositionTopBottom, 0.0d ) );

      this.IndexPositionTopBottom += ( container.Width + this.ContainerPadding );

    }

    internal override void PlaceContainerBackward( Size container,
     bool isGroupContainer,
     out Point containerPosition,
     out double containerProportionInViewport,
     out int layoutProgressionPercentage,
     out double rotateAngle )
    {
      containerProportionInViewport = 1.0d;
      containerPosition = new Point();
      rotateAngle = 0.0d;

      this.IndexPositionBottomUp -= ( container.Width + this.ContainerPadding );

      double distanceFromPathBeginning = this.IndexPositionBottomUp - this.ExtendedViewportStart;

      this.GetPositionForDistance( distanceFromPathBeginning, m_fittingMatrix, out containerPosition, out rotateAngle );

      layoutProgressionPercentage = ( int )( ( distanceFromPathBeginning / m_pathTotalLength ) * 100.0d );

      containerProportionInViewport = this.GetContainerProportionInEffectiveViewport( container, new Point( this.IndexPositionBottomUp, 0.0d ) );

    }

    internal override Point GetBringIntoViewPositionForContainer( Size groupHeaderContainerSize,
      Size itemContainerSize,
      Size viewportSize,
      bool forwardScrolling )
    {
      throw new NotSupportedException( "This method shoudn't be call for the path positionning" );
    }

    internal override double GetScrollOffsetDifferenceBetweenPositions( Point originalPosition, Point targetPosition, Size containerSize )
    {
      throw new NotSupportedException( "This method shoudn't be call for the path positionning" );
    }

    internal override Rect GetCorrectedViewportVisibilityRect( Size stickyHeaderSize, Rect viewportVisibilityRect )
    {
      // The sticky header dosen't have any effect on the 
      // viewport visibility rectangle for a path positioning layout
      return viewportVisibilityRect;
    }

    internal override void UpdateEffectiveViewportSizeInPixels( Size newViewportSizeInPixels )
    {
      this.ViewportCahcedSize = newViewportSizeInPixels;
      if( m_fittingMatrix == null )
      {
        this.UpdateComputedPath();
      }

      double effectivePathLength = m_pathTotalLength / 1.50;
      double oversizedInPixels = m_pathTotalLength - effectivePathLength;
      double nbPixelsToAddEachSide = oversizedInPixels / 2.0d;

      this.EffectiveViewportStart = 0.0d;
      this.EffectiveViewportEnd = effectivePathLength;

      this.ExtendedViewportStart = this.EffectiveViewportStart - nbPixelsToAddEachSide;
      this.ExtendedViewportEnd = this.EffectiveViewportEnd + nbPixelsToAddEachSide;

      this.StartOffsetIndex = this.EffectiveViewportStart;

      this.ResetPositioningIndexes();
    }

    internal override void CorrectViewportSize( double itemsInViewport, ref Size viewportSize )
    {
      // This is because we want every objet to be layout once at the startoffset position.
      // Accodring to the scrollviewer definition, the StartOffset represent the viewport. And
      // this viewport has the size of 1 item.
      viewportSize.Height = 1.0d;
    }

    internal override Point PlaceStickyHeader( Point lastContainerOfTheGroupPosition, Size containerSize, out double angle )
    {
      Point stickyPostion;
      double distanceFromBeginning = this.EffectiveViewportStart - this.ExtendedViewportStart;
      this.GetPositionForDistance( distanceFromBeginning, m_fittingMatrix, out stickyPostion, out angle );
      return stickyPostion;
    }

    #endregion

    #region Protected Internal Methods
    protected internal override double GetContainerProportionInEffectiveViewport( Size containerSize, Point containerPosition )
    {
      // 5 possible cases 
      // #1 container is completly out of the effective viewport (at the top) (0.0)
      // #2 container is completly out of the effective viewport (at the end) (0.0)
      // #3 container is completly in the effective viewport (1.0)
      // #4 container is partially in the effective viewport (at the top) (between 0.0 and 1.0)
      // #5 container is partially in the effective viewport (at the end) (between 0.0 and 1.0)
      double containerDistance = containerSize.Width + this.ContainerPadding;
      double containerStartPosition = containerPosition.X;
      double containerEndPosition = containerPosition.X + containerDistance;
      double sizeOfContainerInViewport = 0.0d;

      if( containerStartPosition < this.EffectiveViewportStart )
      {
        // Case #1 or #4
        if( containerEndPosition < this.EffectiveViewportStart )
        {
          // Case #1
          return 0.0d;
        }
        else
        {
          // Case #4
          sizeOfContainerInViewport = containerEndPosition - this.EffectiveViewportStart;
          return sizeOfContainerInViewport / containerDistance;
        }
      }
      else if( containerEndPosition > this.EffectiveViewportEnd )
      {
        // Case #2 or #5
        if( containerStartPosition > this.EffectiveViewportEnd )
        {
          // Case #2
          return 0.0d;
        }
        else
        {
          // Case #5
          sizeOfContainerInViewport = this.EffectiveViewportEnd - containerStartPosition;
          return sizeOfContainerInViewport / containerDistance;
        }
      }
      else
      {
        // Case 3
        return 1.0;
      }
    }

    internal override double GetGroupHeaderProportion()
    {
      throw new NotSupportedException( "This method shoudn't be call for the path positionning" );
    }

    internal override Size GetCorrectedContainerSize( Size containerSize, Size viewportSize )
    {
      return new Size( containerSize.Width, containerSize.Height );
    }

    #endregion

    #region Private Methods
    private void OnPropertyChanged( object sender, PropertyChangedEventArgs e )
    {
      if( e.PropertyName == "ViewportCachedSize" )
      {
        this.UpdateComputedPath();
      }
    }

    private double GetPathTotalLength( MatrixTransform fitToViewport )
    {
      Point startPoint = fitToViewport.Transform( m_pointsOnFlattenedPath[ 0 ] );
      int count = m_pointsOnFlattenedPath.Count;
      Point currentPoint = startPoint;
      Point nextPoint;
      double totalPathDistance = 0.0d;

      // Make sure we have at least to points
      if( count >= 2 )
      {
        for( int i = 1; i < count; i++ )
        {
          nextPoint = fitToViewport.Transform( m_pointsOnFlattenedPath[ i ] );

          if( nextPoint == currentPoint )
          {
            currentPoint = nextPoint;
            continue;
          }

          // Compute the distance between the current point and the next point
          totalPathDistance +=
            Math.Sqrt( Math.Pow( ( nextPoint.Y - currentPoint.Y ), 2 )
                        + Math.Pow( ( nextPoint.X - currentPoint.X ), 2 ) );

          currentPoint = nextPoint;
        }
      }

      return totalPathDistance;
    }

    private bool GetPositionForDistance( double targetDistanceFromPathBeginning,
      MatrixTransform fitToViewport,
      out Point position,
      out double angle )
    {
      bool foundAPosition = false;
      double actualDistanceFromBeginning = 0;
      double nextDistanceFromBeginning = 0;
      double targetDisplacement = 0;
      Point startPoint = fitToViewport.Transform( m_pointsOnFlattenedPath[ 0 ] );
      int count = m_pointsOnFlattenedPath.Count;
      Point currentPoint = startPoint;
      Point nextPoint;
      position = PositioningFunctionBase.InvalidPosition;
      angle = 0.0d;

      // Make sure we have at least to points
      if( count < 2 )
        return foundAPosition;

      for( int i = 1; i < count; i++ )
      {
        nextPoint = fitToViewport.Transform( m_pointsOnFlattenedPath[ i ] );

        if( nextPoint == currentPoint )
        {
          currentPoint = nextPoint;
          continue;
        }

        // Compute the distance between the current point and the next point
        double distance = Math.Sqrt( Math.Pow( ( nextPoint.Y - currentPoint.Y ), 2 ) + Math.Pow( ( nextPoint.X - currentPoint.X ), 2 ) );
        nextDistanceFromBeginning += distance;

        // If the actualDistanceFromBeginning is greater than the
        // targetDistanceFromPathBeginning
        if( nextDistanceFromBeginning >= targetDistanceFromPathBeginning )
        {
          // We must find the target distance on this segment
          targetDisplacement = targetDistanceFromPathBeginning - actualDistanceFromBeginning;

          // We must split the last segment into intersections of
          // distanceBetweenPoints distance
          double deltaX = ( nextPoint.X - currentPoint.X );
          double deltaY = ( nextPoint.Y - currentPoint.Y );

          double slope = deltaY / deltaX;
          double theta = Math.Atan( slope );

          double ratio = targetDisplacement / distance;
          double x = ratio * deltaX;
          double y = ratio * deltaY;

          // Cmopute the exact position of the container
          position = new Point( currentPoint.X + x, currentPoint.Y + y );


          if( this.ContainerOrientation == ContainerOrientation.OrientOnPath )
          {
            if( ( deltaX >= 0 ) && ( deltaY >= 0 ) )
            {
              angle = ( 180.0d * Math.Atan( slope ) / Math.PI );
            }
            else if( ( deltaX < 0 ) && ( deltaY >= 0 ) )
            {
              angle = ( 180.0d * ( Math.PI + Math.Atan( slope ) ) / Math.PI );
            }
            else if( ( deltaX < 0 ) && ( deltaY < 0 ) )
            {
              angle = ( 180.0d * ( Math.PI + Math.Atan( slope ) ) / Math.PI );
            }
            else if( ( deltaX >= 0 ) && ( deltaY < 0 ) )
            {
              angle = ( 180.0d * Math.Atan( slope ) / Math.PI );
            }
          }

          foundAPosition = true;
          break;

        }
        else
        {
          actualDistanceFromBeginning += distance;
        }

        currentPoint = nextPoint;
      }

      return foundAPosition;
    }

    private MatrixTransform GetFittingMatrix( Size viewport, Stretch stretch )
    {
      double scaleX = 1d;
      double scaleY = 1d;
      double viewportHeightDifferentialOffset = 0d;
      double viewportWidthDifferentialOffset = 0d;
      double offsetX = m_padding.Left;
      double offsetY = m_padding.Top;

      if( stretch != Stretch.None )
      {
        scaleX = ( viewport.Width - ( m_padding.Left + m_padding.Right ) ) / m_pathBound.Width;
        scaleY = ( viewport.Height - ( m_padding.Top + m_padding.Bottom ) ) / m_pathBound.Height;

        switch( stretch )
        {
          case Stretch.Fill:
            offsetX = m_padding.Left - ( m_pathBound.X * scaleX );
            offsetY = m_padding.Top - ( m_pathBound.Y * scaleY );
            break;

          case Stretch.Uniform:

            // Ensure to scale on both axis
            // using the same scale factor
            if( scaleX < scaleY )
            {
              scaleY = scaleX;
              double correctedViewportHeight = viewport.Height - ( m_padding.Top + m_padding.Bottom );
              viewportHeightDifferentialOffset = ( correctedViewportHeight - ( m_pathBound.Height * scaleY ) ) / 2;
              offsetX = m_padding.Left - ( m_pathBound.X * scaleX );
              offsetY = m_padding.Top + viewportHeightDifferentialOffset - ( m_pathBound.Y * scaleY );
            }
            else
            {
              scaleX = scaleY;
              double correctedViewportWidth = viewport.Width - ( m_padding.Left + m_padding.Right );
              viewportWidthDifferentialOffset = ( correctedViewportWidth - ( m_pathBound.Width * scaleX ) ) / 2;
              offsetX = m_padding.Left + viewportWidthDifferentialOffset - ( m_pathBound.X * scaleX );
              offsetY = m_padding.Top - ( m_pathBound.Y * scaleY );
            }

            break;
          case Stretch.UniformToFill:

            // Ensure to scale to 1 the axis
            // requiring the highest scaling
            // factor and scale the other axis
            // proportionnaly to the previously
            // computed scale factors.
            if( scaleX < scaleY )
            {
              scaleX = scaleY;
              offsetX = m_padding.Left - ( m_pathBound.X * scaleX );
              offsetY = m_padding.Top - ( m_pathBound.Y * scaleY );
            }
            else
            {
              scaleY = scaleX;
              offsetX = m_padding.Left - ( m_pathBound.X * scaleX );
              offsetY = m_padding.Top - ( m_pathBound.Y * scaleY );
            }
            break;
        }
      }
      else
      {
        offsetX = m_padding.Left + ( m_pathBound.X * scaleX );
        offsetY = m_padding.Top + ( m_pathBound.Y * scaleY );
      }

      Matrix transformationMatrix = new Matrix( scaleX, 0, 0, scaleY, offsetX, offsetY );
      MatrixTransform matrixTransform = new MatrixTransform();
      matrixTransform.Matrix = transformationMatrix;

      return matrixTransform;
    }

    private void UpdateComputedPath()
    {
      m_fittingMatrix = this.GetFittingMatrix( m_viewportCachedSize, this.Stretch );

      m_pathTotalLength = this.GetPathTotalLength( m_fittingMatrix );
    }

    #endregion

    #region Private Members
    // Path positioning members
    private List<Point> m_pointsOnFlattenedPath;
    private Rect m_pathBound = new Rect( new Point( 0, 0 ), Size.Empty );
    private double m_pathTotalLength = 0.0d;
    MatrixTransform m_fittingMatrix = null;

    // Layout state members
    private Size m_viewportCachedSize = Size.Empty;
    private bool m_firstContainerLayouted = false;
    private double m_cachedPartialOffset = 0.0d;
    private Size m_cachedItemContainerSize = new Size( 0.0d, 0.0d );
    #endregion
  }
}
